back -
derivations"BK." A complimentary term used
in conjunction with the term ahead"
to label station equations. The back station signifies
the stations behind the equality on
a chain: -L- Sta 11+23.34 BK = -LREV- Sta
25+62.31 AH.
base course -
Pavement Layer between the surface course or intermediate
course layer and the subgrade (fine grade and compacted soil). Common base course:
SP B25.0B and ABC.[image]
beam -
synonym: girder. Steel or concrete superstructure
members placed length wise along a
bridge. Generally located between the bridge concrete
slab and bent cap. Span types:
Prestressed Cored Slab, Prestressed Girder, Prestressed
MBT, Prestressed Box Beam, I-Beam, and Plate Girder.[image]
bearing -
Angle measurement used to label direction for horizontal
alignments. Format: {North
or South} {Angle in Degrees° Minutes' Seconds"
from Respective N or S Axis}{East
or West}; [examples:
N
58° 36' 55.4" E S
45° 22' 38.7" W]. For English projects,
the accuracy of bearings is to the
tenth of a second; N 11° 22' 33.4" E.
For Metric projects, it is to the
hundredth of a second; N 11° 22' 33.44' E.
Due
North is N 0° E or W; Due
South is S 0° E or W; Due
East is N or S 90° E;
Due West is N or S 90°
W.
bent -
type: interior and end bents. Bridge substructure
composed of bent caps, columns, piles,
and footings.[image]
binder course -
synonym: intermediate course. Pavement Layer
between the surface course layer and
the base course layer.[image]
bridge -
synonym: structure. A structure 20 ft or more
constructed to span over roadways,
other bridges (flyovers), streams, wetlands, railroads,
or any condition which requires a
grade separation.. Other types: Cored slab: Cored
slab bridges are noted because the bridge slab spans
are cored or hollowed out.[image]
broken back curves ƒ3-
synonym:
flat back curves. The arrangement of two curves
with a short tangent deflecting in
the same direction. During night time driving
or limited sight distance conditions, drivers normally
do not expect successive turns in
the same direction.Use of compound curves or a spiral
transition is recommended in place of broken back curves.